title: Cloning and characterization of the retinoic acid receptor-like protein in the rock shell, Thais clavigera.
abstract: The organotin compounds have a high affinity for the retinoid X receptor (RXR), which is a transcriptional factor activated by retinoids that induce imposex in gastropods. However, the molecular mechanisms underlying the regulation of RXR and its related genes in gastropods remain unclear. We isolated a retinoic acid receptor (RAR)-like cDNA (TcRAR) in the rock shell, Thais clavigera, and examined the transcriptional activity of the TcRAR protein by using all-trans retinoic acid (ATRA). However, we did not observe any ligand-dependent transactivation by this protein. We also examined the transcriptional activity of the TcRAR-ligand binding domain fused with the GAL4-DNA binding domain by using retinoic acids, retinol, and organotins and again saw no noteworthy transcriptional induction by these chemicals. Use of a mammalian two-hybrid assay to assess the interaction of the TcRAR protein with the TcRXR isoforms suggested that TcRAR might form a heterodimer with the RXR isoforms. The transcriptional activity of domain-swapped TcRAR chimeric proteins (the A/B domain of TcRAR combined with the D-F domain of human RARα) was also examined and found to be ATRA-dependent. These results suggest that TcRAR is not activated by retinoic acids, but can form a heterodimer with TcRXR isoforms. These data contribute to our understanding of the mechanism by which RXR functions in gastropods.
authors.affiliation: Center for Environmental Risk Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Urushitani
authors.forename: Yoshinao
authors.initials: Y
authors.lastname: Katsu
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Ohta
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Shiraishi
authors.forename: Taisen
authors.initials: T
authors.lastname: Iguchi
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Horiguchi
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D049851:Gastropoda / Q000187:drug effects / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects; D018168:Receptors, Retinoic Acid / Q000235:genetics* / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D018168:Receptors, Retinoic Acid; D014212:Tretinoin
keywords: Imposex; Reporter gene assay; Retinoic acid receptor (RAR); Retinoid X receptor (RXR); Rock shell; Thais clavigera